Change 'render' to 'builder'

**Is your feature request related to a problem? Please describe.**
This is to standardize closely to Flutter widgets that use a builder function rather than a render function.

**Describe the solution you'd like**

1. **renderLoad** becomes **buildLoad**
2. **renderError** becomes **buildError**
3. **renderSuccess** becomes **buildSuccess**

**Describe alternatives you've considered**
N/A

**Additional context**
Add any other context or screenshots about the feature request here.